The SOMM Journal

June / July 2017

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120 { THE SOMM JOURNAL } JUNE/JULY 2017
WINE STYLES INFLUENCED
BY MLF CAN BE EITHER
{
scents & accountability
}
SUMMER WEATHER IS CONDUCIVE to classic Vinho
Verde, a youthful wine style from northern Portugal that
is defined in part by the refreshing and intentional prickle
from trapped CO
2
that historically originated from malolactic
fermentation (MLF) taking place in the bottle. Modern-day Vinho
Verde producers have resorted to completing MLF prior to bot
-
tling to avoid the sediment that is its inevitable by-product and
adding CO
2
to mimic its prickle.
Malolactic fermentation is a conversion, also referred to as res-
piration, that takes place when the family of lactic acid bacteria
(LAB) that can include
Oenococcus oeni and various species of
Lactobacillus and Pediococcus ingest malic acid and respire lactic
acid, liberating carbon dioxide in the process. As it's a naturally-
occurring process, MLF fermentation has been around as long
as fermentation itself. However, the manipulation of MLF either
by suppressing, limiting or initiating it is a relatively new practice
ascribed to modern winemaking.
Because MLF reduces acidity and raises pH in finished wine,
typically reducing titratable acidity (TA) by 1 to 3 g/l and increasing
pH by 0.3 units, it's not suitable for all wine styles. In varieties like
Riesling and Gewürztraminer it's considered a fault, and although
almost all still red wines undergo MLF, if it occurs in bottle where
CO
2
can be trapped, the only way to describe the result is spoilage.
What surprises fans of Chardonnay styles from both ends of
the spectrum—from steely and austere to dripping butter—is
that they both rely on MLF for their charm and popularity. How
is it that Chablis, a wine style that often undergoes 100 percent
MLF, remains free from the buttery, creamy characteristics so often
associated with New World Chardonnay?
Although yogurt is a common descriptor for Chablis that points
to MLF, in its absence it's a guessing game as to whether MLF
was employed. Wines from cooler growing regions such as Chablis
naturally have higher levels of malic acid, making MLF an important
technique for de-acidification and enhancing body and mouthfeel.
MLF has also been seen to reduce excessive vegetative and grassy
notes in wines made from underripe grapes.
But in Chablis, malic acidity is off the hook; it's the conversion
of citric acid by LAB, notably Pediococcus species, that creates
diacetyl. The higher the initial concentration of citric acid, the more
diacetyl will be produced during MLF. Winemakers manipulate
MLF by choosing when to inoculate, working anaerobically to keep
concentrations of diacetyl low and keeping the wine on its lees,
employing the Burgundian winemaking practice of bâtonage, to
allow both yeast and LAB to convert any diacetyl to yogurt-like
acetoin and odorless 2, 3 butendiol.
Chardonnay oozing diacetyl, more reminiscent of movie pop
-
corn than the Chardonnay grape, is a wine style that met its height
of popularity in the 1980s and encountered a backlash in the
1990s but has preserved. While diacetyl rarely faults Chardonnay,
the industry has since seen a shift in style towards less apparent
MLF characteristics. Fans of the overt style have wine brands—
most notably JAM Cellars' Butter—that clearly communicates this
style and caters to their tastes.
In red wine production, MLF is de rigueur for increasing the
polymerization of tannins and anthocyanins and for reducing astrin
-
gency. When MLF takes place in an oak barrel, LAB enzymes react
with soluble substances creating enhanced aromas of spice, smoke,
roasted and chocolate notes. However, MLF can reduce primary
fruit aromas and impact color in addition to being the source of a
host of flaws and faults (previously discussed here) among them
bitterness or amertume, Geranium taint, ropiness or graisse, mousi
-
ness, mannitol (artificial sweetness) and refermentation.
It'
s no surprise that winemakers prefer to inoculate for MLF with
O. oeni, steering clear of Lactobacillus and Pediococcus to avoid off
flavors and corrections. When they do, consumers should expe-
rience fewer red wine headaches, which are likely caused by a
reaction to the biogenic amines,
ammonia derivatives, produced
by Pediococcus.
Fashion or Faux Pas?
The genus Lactobacillus currently contains over 180 species.
by Deborah Parker Wong